That is an earlier S-Class and a sedan. If you have an SEC that is a coupe. We are talking about the W126 chassis which was produced in the '80s. The later S-Class chassis W140 began in about 1990. This is from memory so please don't quote me.

<edit> I just noticed MB also used the SEL designation on an even older S-Class, the W116 (1973-1980).